The present invention relates generally to micro fabrication techniques. More particularly, the invention provides a method and device for manufacturing a fluidic pumping device using a micromachining method and apparatus. Merely by way of example, the invention has been applied to the manufacture of a polymer based fluidic pumping device using electrostatic energy. But it would be recognized that the invention has a much broader range of applicability. For example, the invention can be applied to other applications.
A Micro-Electro-Mechanical System, commonly called MEMS, is generally a batch-fabricated (micro fabricated) system that includes both electrical and mechanical elements. MEMS elements often have characteristic sizes ranging from nanometers to millimeters. MEMS often makes possible certain systems that are smaller, faster, more economical, and energy efficient in some cases. In a general MEMS system, the electrical portion includes integrated circuits, which forms the thinking part, while the electro-mechanical portion works with the thinking part to control functions and perception.
MEMS generally includes micro sensors and actuator devices. Micro sensors often gather outside information such as thermal, biological, optical, gravitational, and others. Actuators often respond to user based information to control their environment. As merely an example, fluidic pumping devices are common examples of MEMS. Such pumping device often rely upon external fluidic drive sources to selectively move fluids through various channel regions. These external drive sources are often cumbersome and lead to inefficiencies. Other pumping devices use drive forces such as electrophoresis. Electrophoresis relies upon a pair of electrodes that are in direct contact with the working fluid. As such, electrophoresis has many limitations. These and other limitations can be found throughout the present specification and more particularly below.
Conventional micro pumps are either bulk micro machined or power thirsty or complexly packaged so they are not suitable for total system integration. Examples have been illustrated in G. T. A Kovacs, “Micro machined Transducers Sourcebook”, McGraw-Hill (1998); P. Sethu and C. H. Mastrangelo, “Polymer based Actuator for nozzle-diffuser pumps in Plastic Microfluidic Systems”, pp325–328 (2002); J. H. Tsai and L. W. Lin, “A Thermal Bubble Actuated Micro Nozzle-Diffuser Pump”, MEMS 2001, pp. 409–412; J. W. Judy, T. Tamagawa and D. L. Polla, “Micromechanical Membrane Pump”, MEMS 1991, pp.182–186; and C. Grojean, X. Yang and Y. C. Tai, “A Thermopneumatic Peristaltic Micropump”, Transducers, pp1776–1779 (1999).
From the above, it is seen that techniques for manufacturing improved MEMS devices is highly desirable.